Internal bleeding (also known as internal hemorrhage), namely the leaking of blood from the vascular system into body cavities or spaces, is a major, potentially life-threatening complication associated with invasive medical procedures.
Examples of invasive and minimally invasive medical procedures that are associated with a profound risk of internal bleeding include coronary angiography and catheterization, percutaneous coronary intervention, a caesarean section, percutaneous biopsies (e.g. liver, kidney, lung), laparoscopic procedures and coronary artery bypass grafting.
Post-operative surgical site bleeding is another major cause of concern. Intra peritoneal bleeding after an abdominal surgery may lead to unnoticed hypo-volemic shock. Pericardial bleeding after cardiac surgery may lead to space occupying hematoma and pericardial tamponade.
Internal bleeding may also occur as a result of internal trauma and injuries of the human body. Internal bleeding may also result from medical conditions associated with an increased risk of bleeding. For example, a medical condition in which development of internal bleeding is a serious risk is a cranial intra-ventricular hemorrhage (IVH) in premature neonates. Several studies estimated that the risk for IVH in very low birth weight neonates is 20-25%; many of these will suffer severe neurodevelopmental sequelae. Early diagnosis of IVH may allow early treatment and late disability prevention.
Diagnosis of internal bleeding is often problematic, since symptoms may not be evident until a significant amount of blood is lost and/or a blood clot is formed that is large enough to press adjacent organs and disrupt their proper functioning. Furthermore, after medical procedures, most patients suffer physical pain and blurred awareness which overcome the sings of internal bleeding. In addition to internal bleeding, invasive procedures may lead to additional changes to the body tissues at the operation area, including for example edema, which may complicate the detection and correct diagnosis of bleeding and hematoma. Early detection of internal bleeding is desired, as it may facilitate optimal treatment and prevention of mortality.
Hemoglobin in red blood cells absorbs near infra-red (NIR) light. Extra-vascular blood is more concentrated compared to intra-vascular, thus absorbing more NIR light. Several blood analytes, including for example urea, triglycerides, cholesterol, glucose, total protein and albumin, are known to absorb mid infra-red (MIR) light. MIR at certain wavelengths is generally not absorbed by the surrounding tissue (Shaw and Mantsch 2008 “Infrared spectroscopy in clinical and diagnostic analysis”; In: Encyclopedia of Analytical Chemistry, edited by Robert A. Meyers, John Wiley & Sons Ltd, Chichester, pp. 1-19; Klonoff et al. 1998 IEEE Photonics Society, vol. 12(2) April Newsletter; Hazama et al. 2008 “High-energy pulsed tunable mid-infrared laser aids biomedical applications”, SPIE Newsroom; and Arai et al. 1990 “infrared absorption spectra ranging from 2.5 to 10 μm at various layers of human normal abdominal aorta and fibrofatty atheroma in vitro”, Lasers in Surgery and Medicine, 10(4); 357-362).
Water content in body tissues affects dielectric properties of the tissues, reflected in their varying interaction with radio-frequency (RF) radiation (Werber et al. 2006 “Investigation of RF transmission properties of human tissues”, Advances in Radio Science, 4: 357-360; Smith et al. 1985 “Dielectric properties of low-water-content tissues” Phys Med Biol. 30(9):965-73; and Hofmann et al. 2011 Proc. IEEE Int. Symp. Medical Meas. Applications, Bari, Italy, pp. 39-42).
U.S. Pat. No. 5,694,938 discloses non-invasive near infrared optical medical imaging devices for both hematoma detection in the brain and early tumor detection in the breast. This is achieved using image reconstruction which allows a mapping of the position dependent contrast diffusive propagation constants, which are related to the optical absorption coefficient and scattering coefficient in the tissue, at near infrared wavelengths.
U.S. Pat. No. 5,954,053 is directed, inter alia, to detection of brain hematoma and discloses systems that utilize differential measurement of radiation that has migrated through migration paths between two source-detector pairs placed on the head in a manner that each path is localized in a portion of one hemisphere of the brain.
U.S. Pat. No. 6,175,759 discloses a non-invasive multispectral energy system made up of a transilluminating radiating means that illuminates soft tissues that have been treated with a contrast agent using first and second near-IR illuminating signals to produce thereby a first and second near-IR multispectral images; means for optically combining the first and second near-IR multispectral images into a combined tissue image; and a means for processing the combined tissue image to detect cancer and tumors and internal bleeding.
U.S. Pat. No. 6,233,479 discloses a non-invasive device designed to detect and localize blood pooling and clots near the outer surface of the body. While being geared towards finding sub-dural and epi-dural hematomas, the device can be used to detect blood pooling anywhere near the surface of the body. The device is based on low power pulsed microwave technology combined with a specialized antenna, signal processing/recognition algorithms and a disposable cap worn by the patient which will facilitate accurate mapping of the brain and proper function of the instrument.
U.S. Pat. No. 6,875,176 discloses systems and methods for assessment of tissue properties, noninvasively, by acquiring data relating to at least one aspect of intrinsic and/or induced tissue displacement, or associated biological responses. Data relating to tissue displacement and associated biological changes may be acquired by detecting acoustic properties of tissue using ultrasound interrogation pulses, preferably in a scatter or Doppler detection mode. In some embodiments, detection techniques, including near-infrared spectroscopy (NIRS), magnetic resonance techniques, acoustic hydrophones and the like, are also used.
US 2009/0221919 (now U.S. Pat. No. 8,060,189) discloses, inter alia, a device for intra cranial hematoma detection, in head trauma settings, using the differences in NIR light absorbance between the two cranial hemispheres that may appear when blood accumulates in one cranial hemisphere.
JP 2009136436 discloses an internal hemorrhage detecting apparatus comprising an armrest for placing an arm, a near infrared LED for irradiating the arm rested on the armrest with near infrared rays, and a near infrared camera for continuously imaging a position of the arm to which the near infrared rays are applied. An analysis range is extracted from a comparison image captured by the near infrared camera, and the area of the position where the luminance is lower than a prescribed threshold is found. Blood is determined to be present in other regions than veins if the area is increased by a prescribed quantity.
There is still a need in the art for devices, systems and methods for early detection of internal bleeding and hematoma formation in body parts of interest, particularly following invasive procedures. For example, it would be highly beneficial to have devices, systems and methods for non-invasively monitoring a patient following an invasive procedure in order to detect internal bleeding as early as possible after it begins, while distinguishing between bleeding and other changes to tissues, such as formation of edema.